When we're searching for the right word to say, or we don't know what to say or how to say something, this happens.

(SOUNDBITE OF ARCHIVED RECORDING)

UNIDENTIFIED PEOPLE: Um - uh...

MELISSA BLOCK, HOST:

Among those uttering the ums and uhs there were President Obama, Hillary Clinton, Woody Allen and Meryl Streep.

SIEGEL: And it turns out that some people are more apt to say uh. Others lean more on um. Some years back, a linguist made an observation about that.

MARK LIBERMAN: Men use uh more than women do. Women use um more than men.

SIEGEL: That is Mark Liberman of the University of Pennsylvania. He discovered the um and uh correlation by analyzing thousands of transcribed telephone conversations. He adds that ums go by the wayside as we mature.

LIBERMAN: As everybody grows older, they use uh more and um less.

SIEGEL: And since Liberman made his original observations, others have dug into the data. And he wrote in his Language Log blog last week that they've confirmed and amplified what he found.

BLOCK: He points out that making sense of this gender divide on verbal fillers isn't easy.

LIBERMAN: One explanation would be that it's just a gender marker - a gender identity marker, like, you know, wearing makeup or something like that. It's also possible that there's something a little bit deeper going on. Maybe um and uh have slightly different functions.

SIEGEL: For instance, maybe those who are more likely to say uh are searching for what to say.

BLOCK: And the others, um, trying to figure out how to say it.

SIEGEL: And the findings also show a sort of verbal compromise.

BLOCK: When men and women talk to each other, males use uh less and females use uh more.